Vulnerability Description
SandboxJS is a JavaScript sandboxing library. Prior to 0.8.31, a sandbox escape vulnerability allows sandboxed code to mutate host built-in prototypes by laundering the isGlobal protection flag through array literal intermediaries. When a global prototype reference (e.g., Map.prototype, Set.prototype) is placed into an array and retrieved, the isGlobal taint is stripped, permitting direct prototype mutation from within the sandbox. This results in persistent host-side prototype pollution and may enable RCE in applications that use polluted properties in sensitive sinks (example gadget: execSync(obj.cmd)). This vulnerability is fixed in 0.8.31.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Nyariv | Sandboxjs | < 0.8.31 |
Related Weaknesses (CWE)
References
- https://github.com/nyariv/SandboxJS/commit/f369f8db26649f212a6a9a2e7a1624cb2f705Patch
- https://github.com/nyariv/SandboxJS/security/advisories/GHSA-ww7g-4gwx-m7wjExploitMitigationVendor Advisory
FAQ
What is CVE-2026-25881?
CVE-2026-25881 is a vulnerability with a CVSS score of 9.0 (CRITICAL). SandboxJS is a JavaScript sandboxing library. Prior to 0.8.31, a sandbox escape vulnerability allows sandboxed code to mutate host built-in prototypes by laundering the isGlobal protection flag throug...
How severe is CVE-2026-25881?
CVE-2026-25881 has been rated CRITICAL with a CVSS base score of 9.0/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-25881?
Check the references section above for vendor advisories and patch information. Affected products include: Nyariv Sandboxjs.